<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        table {
            border: 1px solid #000;
            text-align: center;
            width: 240px;
        }

        th,
        td {
            border: 1px solid #000;
        }

        h3 {
            position: relative;
        }
    </style>
</head>

<body>

    <div id="app">
        <h3>小黑的礼物清单</h3>
        <table>
            <tr>
                <th>名字</th>
                <th>数量</th>
            </tr>
            <tr v-for="(item, index) in list" :key="item.id">
                <td>{{ item.name }}</td>
                <td>{{ item.num }}个</td>
            </tr>
        </table>

        <!-- 目标：统计求和，求得礼物总数 -->
        <p>礼物总数：{{sum}} 个</p>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
    <script>
        const app = new Vue({
            el: '#app',
            data: {
                // 现有的数据
                list: [
                    { id: 1, name: '篮球', num: 1 },
                    { id: 2, name: '玩具', num: 2 },
                    { id: 3, name: '铅笔', num: 5 },
                ]
            },
            computed: {
                sum() {

                    // 数组求和，使用reduce
                    let sum = this.list.reduce((sum, item) => sum + item.num, 0);
                    return sum
                }
            }
        })
    </script>
</body>

</html>